Effects of angular pump mismatch for the semi-linear oscillator

Abstract

We investigate, analytically and numerically, the influence of an angular mismatch of counter-propagating pump beams on the threshold of oscillation for the photorefractive semi-linear oscillator driven by non-local non-linear response. Our analysis includes the frequency degenerate and non-degenerate regimes within a wide range of the variable input parameters—the coupling strength, the pump ratio, and the feedback mirror reflectivity. The limiting case of mirrorless oscillation is considered as well. The main outcome of our studies is the possibility of strong reduction of the oscillation threshold owing to the angular mismatch. Furthermore, increasing the mismatch induces pronounced bifurcations of the oscillation parameters, including transitions between degenerate and non-degenerate oscillation modes. The main findings are verified by direct simulations of the dynamic equations.